


The King and His Plumber

by Pastel_Hexagons



Category: Luigi's Mansion (Video Games), Super Mario Bros. (Video Games)
Genre: Alternate Universe - Canon Divergence, Awkward Crush, Enemies to Lovers, Fluff and Angst, Guilty Pleasures, Headcanon, Humanized King Boo, M/M, Other Additional Tags to Be Added, Slow Build, Slow Burn, lots and lots of headcanons, sort of ooc
Language: English
Status: In-Progress
Published: 2020-02-09
Updated: 2020-02-19
Packaged: 2021-02-28 05:28:32
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 3,671
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22639255
Author URL: https://archiveofourown.org/users/Pastel_Hexagons/pseuds/Pastel_Hexagons
Summary: A boo falling in love with a human, Was that even possible?Yes.Yes it was, and King Boo absolutely despised every single bit of it.
Relationships: King Boo/Luigi
Comments: 29
Kudos: 87





	1. Chapter 1

**Author's Note:**

> Hey, what do you get when you decide to binge-play all the Luigi Mansion series? This fic apparently!
> 
> But in all seriousness, I honestly really wanted to type and get this fan fiction out as I felt that there were hardly any Luigi/King Boo fan fictions out there. (So, I took matters into my own hands!)
> 
> So, I hope that you enjoy it! ^_^
> 
> Also this takes place in the original Luigi's Mansion!

This _wasn't_ supposed to happen.

It wasn’t _meant_ to happen-.

_It’s impossible._

Within the basement of the mansion resided King Boo, floating back and forth ever so relentlessly in front of Mario’s painting. His nubs clasped ever so tightly together behind his back. 

God, he could feel himself blushing and he absolutely hated it. Well, at least Mario was asleep. He honestly couldn’t bring himself to imagine all of the embarrassment it would have brought upon him if a living being, nonetheless Mario, caught the king of all boos blushing. 

Maybe he would have laughed at the boo’s minor predicament, possibly even calling him cute or adorable in some weird twisted way.

That was the problem.

He wasn’t supposed to be called adorable nor was he supposed to be labeled as “cute". He was supposed to be frightening, almost downright terrifying.

The king paused in his tracks.

He wasn’t also supposed to develop a crush on the person he was trying to capture.

And with that statement, the lovestruck boo let out a drawn-out high pitched whine as he plunged from the air, face first, into the ground. His soft marshmallow-Esque body meeting with the hard gritty cobblestone as his crown proceeded to roll a couple of inches away from him as a result of the impact of the fall.

‘Ugh, Why did it have to be this way?’ He found himself repeating this phrase to himself.

_‘Why did he have to fall in love with Luigi?’_

Of course, it wasn’t always like this as whenever the two first met, King Boo absolutely despised Luigi. He often found himself making dozens of snarky remarks towards the plumber whenever they crossed paths, or simply plain out terrorizing him in any way possible. With insult after insult, and from countless mice and spiders scattered all across the mansion frightening Luigi, it truly never got old for King Boo. He enjoyed every single second of doing so, especially the reactions he would get out of Luigi. Now those, those were priceless.

However, like all good things, his enjoyment in taunting and terrorizing Luigi came to an end.

As Luigi continued with his journey, traversing through endless hallways of the decomposing mansion searching for his lost brother, the boo noticed something.

_Luigi changed._

With every room and floor he cleared of ghosts, the plumber became a little bit more confident. Believing that he was one step closer in reuniting with Mario. Of course, he was still somewhat anxious from time to time but that was about it.

It was almost like Luigi was a completely different person from who originally walked in through the mansion’s vast doors.

King Boo even experienced firsthand for himself as he decided to pay Luigi another visit to once again ‘congratulate’ him on what a ‘fantastic job’ he’s doing. (You know, from capturing countless 'innocent' ghosts to raiding every room in the mansion for treasure. The usual.) He couldn’t even contain his excitement as before appearing in front of Luigi, he tried his best to imagine how terrified Luigi would look this time. 

Would he scream?

Would he run away?

No.

None of it happened.

Whenever King Boo finally managed to manifest himself in front of Luigi, all Luigi seemed to do was flinch. Hell, whenever the boo decided to go on his nonsensical spiel, Luigi still didn’t budge. (Yes, of course, he was trembling just a tiny bit, and his breathing was possibly uneven, but not once did he decide to run away or even to call for help for that matter.)

He just stood still with a somewhat neutral facial expression plastered upon his face.

And from that moment, King Boo noticed something. Something that was quite rare.

Luigi was no longer afraid of him. (Well, almost but that was beside the point.)

Maybe that's the reason why he developed such feelings for a person he once despised, he thought. It’s not every century that you encounter a living being who isn’t afraid of ghosts or even the king of ghosts to be more precise.

Yeah, maybe that was it.

Maybe that's the reason wh-

"Is everything alright my King?”

The boo’s eyes widen as he was snapped out of his deep thought and was brought back to reality. He immediately sprung up from the floor and went back to floating in mid-air. Occasionally, dusting pieces of rocks and gravel off of his body to appear more “professional” as in front of him were two boos. Each one looked more distressed than the other.

“We heard you screaming throughout the mansion your highness, is everything okay? - Did Mario manage to escape?”

King Boo took a deep breath before speaking, “N-no, no, everything’s fine. Mario is still here safe and sound, he did not escap-”  
  
He froze.

“Wait-you said that you heard me screaming throughout the whole entire mansion?”

“Yes, of course, my liege,” The other boo spoke up, “About almost everyone in this establishment heard it.”

Everyone? Oh God please don’t tell me-

“E-everyone? Does that ‘everyone’ include Lui-”

“ Luigi? Yes, M’lord”

“Fuck.” King Boo muttered underneath his breath as once again he felt himself blushing. Possibly even more profusely than before as now, he knows his ~~newly found crush~~ Luigi heard him whining throughout the mansion all simply due to him being lovesick.

One of the boos let out a gasp, "W-was Luigi supposed to not hear you, my lord?!- I swear it was dark in the hallway that I found him in but I surely saw his reaction. He simply shrugged it off, I swear, he thought the sound to be the wind-"

"No," King Boo sighed, eyes darted to the side to avoid the glance of the other boos, "It's fine."

"Are you sure? I mean we can probably bring Luigi up here so you can confront him-"

He facepalmed, "No, as I said, it's fine," his voice grew more stern, "just, just pretending that my sudden “outburst’ and this conversation never happened…"

The room was silenced as both boos looked up at their king who was shielding his face before looking back at each other and shrugged. Although their king was clearly in some way or form in distress, there was nothing the boos could do about it. The king liked to be left alone to his problems as he believed he’s the only one capable of solving them and he wanted no one to interfere. So, the best thing the two boos could do at the moment was to leave him alone.

And that’s what they did.

Each boo turned around and made their way towards the entrance, but just as they were about to dissipate into the walls-

“Wait.”

Both boos turned around to see their King, still sporting a very faint blush.

“You know what, bring Luigi here at once.”

And with that, the boos happily nodded before making their way out of the room.

King Boo sighed before turning around to pick up his crown off of the ground and placing it back onto his head, checking in one of the countless mirrors in the room making sure it was perfectly straight.

Was he making a horrific decision inviting Luigi to his hideout and possibly even confessing his love to the plumber? Possibly, but he also couldn’t keep living like this, with his little ‘crush’ of his getting in the way of things. Not to mention what was the worst that could happen? He’s already dead.


	2. Chapter 2

**Notes for the Chapter:**

> Before this chapter begins, I just want to make a couple of annoucements! (^_^)
> 
> First of all, thank you all for your support and kind comments! I cannot truly express my gratitude enough!
> 
> Second, Human!KB's design is based upon multiple things, mainly headcanons and inspirations, and instead of trying to explain his apperance heavily in detail, I whipped up a quick little doodle within my notes (^_^)b
> 
> https://imgur.com/a/EvVjF4T 
> 
> With all that being said, let's get on with the chapter:

Their task given to them by their king was proven to be quite tedious to say the least. Not only did they have to traverse through the mansion, checking every room and floor for signs of the green plumber, but once they did finally manage to find Luigi, before either of them could get a single word out of their mouths explaining why they were here, they were immediately greeted to the poltergust as Luigi attempted to vacuum both of them up.

What was once going to be a simple conversation turned out to be a full-blown game of cat and mouse as the boos scampered across the room, overturning and possibly even breaking countless pieces of furniture as they tried to avoid the vacuum's powerful suction. While at the same time still attempting to get their point across to Luigi that they didn't mean any harm.

Luckily after countless minutes of nonsensical screaming, vacuuming, and home wrecking, something within Luigi clicked. He proceeded to turn off the poltergust and lowered the wand and placed it by his side, shifting his focus to the two exhausted boos who laid idly on the carpet floor. After managing to catch and steady their breaths, they once more, explain to Luigi why exactly they were here, stating that King Boo sent both of them in order to retrieve him.

Although a tad bit sceptical of their story at first, Luigi hesitantly but surely agreed to go with the ghosts as he felt that they were honestly telling the truth. Nonetheless, he kept a firm grip on the poltergust. (You could never be too careful whenever it came to boos..)

And so there they were, all three of them traversing through a narrow corridor as they made their way towards the basement. Luigi was in the middle of the gritty pathway as the two boos were on either side of him.

"So, _he_ wanted to see me huh? Do you guys have any ideas why?" Luigi asked the boo on his right.

" _..Sorry for also trying to vacuum you guys up by the way…_ " he chuckled nervously.

"It's fine," The boo responded, "You were probably on edge whenever we first appeared, that I can understand. But why our king wanted to see you, particularly _alive_ , is something I can't fully wrap my head around."

Luigi placed a hand over his chest and sighed, feeling quite relieved.

_'He wanted to see me alive? Well, at least that's some good news.'_

"But hey, don't sweat it," the boo continued, " it's probably not that big of a deal as not only did he want you _alive_ , but before hand he appeared to be quite flustered by the fact that you heard his little cry of pity across the mansion. Which, if I put two and two together... I guess I can somewhat say that he _may_ have developed a crush on you…"

Luigi's heart nearly stopped as he heard the ghost mentioning that King Boo, of all people, possibly has a crush on him. He began to sport a faint blush across his face as his cheeks gradually grew slightly warmer with every step he took.

‘Could a ghost, nonetheless a boo, love a human? No, it was absurd! He never heard anything like it. Not in the history books of the Mushroom Kingdom, not from the civilians who inhabit it, and especially not from the princess herself.’

"H-he has a crush?! On me? But that's just absurd!" The plumber exclaimed, pointing to himself.

"Maybe, maybe not. It was only a superstition I had for a while, and for a while I mean in the past hour or so. But if my guess is right, I can kind of see the reasoning behind him wanting to meet up with you as I can envision him probably wanting to confess his love to yo- OW!" The boo yelp in response to the other ghost backhanding him.

"What about our assignment did you not understand?" The other hissed, "We were supposed to drag Luigi from point A to point B, that's it. We weren't supposed to talk about sensitive matters regarding the king. That's none of your business, that's none of my business, and it's especially none of his business either."

"Well, I'm sorry," the boo responded halfheartedly, rubbing the back of his head, "I didn't know you were such a _teacher's pet_.”

"Oh really?! Now we're just hurling insults are we? Why I ought of-"

But before things could get ugly, Luigi intervene the two's squabble by waving his gloved-hand frantically in front of both of their faces.

"Guys, guys, calm down. There's no reason to get aggressive!" The plumber stated, "Besides, we're here already." 

He pointed to the rusty door in front of them.

"..."

One Boo deeply exhaled, "Well then, it's settled. Let's put all this childness behind us."

"Agreed."

The two boos proceeded to gather in front of Luigi as they gesture towards the cobblestone wall.

"Well then, after you Luigi.."

"Uh guys," Luigi responded sheepishly, rubbing the back of his neck, "I'm not a ghost, I can't go through walls, I use doors remember.."

"..Oh yeah. Well then, feel free to use the door if you’d like.”

As Luigi scooted passed the two and made it inside the room, he could see King Boo, floating a couple feet ahead of him, straightening out Mario's portrait on the wall. He clearly wasn't that much bigger than a regular boo, but that didn’t mean that he should be treated the same as one as there was just something ominous about his presence that kept Luigi on his guard whenever he's near.

"We brought him here your majesty."

King Boo turned around, clasping his nubs together in gratification. 

"Ah yes, I knew I could trust you two. Now, if you'll excuse us," he eyed the plumber, " Luigi and I have some catching up to do." 

Neither boo budged as each one had a huge grin plastered on their faces.

He sighed, " _Alone_." Guestering a shooing motion towards the entrance.

"Oh! Got it your majesty," one boo spoke up and winked towards the other, " _We'll leave you two be then._ " And with that, both boos seemed to vanish almost instantly.

...

"You guys know I can still _feel_ your presence right?” King Boo spoke out, “Leave.”

Luigi rapidly swerved his head to the side as he could have sworn that he heard an audible groan right beside him.

After allowing a couple of seconds to pass, ensuring himself that it was only them two residing within the room, the boo finally spoke.

"Listen Luigi, I know you may be wondering why I want yo-"

"Oh, I know _exactly_ what you want," Luigi interrupted, his voice quivering as he pointed the poltergust directly at the spirit, "You're going to allow Mario his freedom if I agree to take his place within the painting. Well guess what, it's not gonna happen. Both of us are leaving the mansion _together no matter what._ " 

The king paused for a few moments before bursting out into laughter as he approached the plumber, placing one nub on the vacuum's head and pushed gently down, all while not breaking eye contact.

"Now now, no need to get all hostile Luigi. Although that sounds like a wonderful idea, I simply have to agree, that’s not the reason why I wanted to see you. My boos did tell you that all I wanted to do was to have a chat did they not? So, if that’s the case, there's no reason for you to go crazy with that 'horrendous' thing you call a vacuum strapped to your back.." 

He floated a couple of inches back, "Now, what I _was_ going to say before I got _rudely_ interrupted was that you may be wondering _why_ exactly I called you here."

"Which is?" Luigi questioned, setting the poltergust’s wand by his side, still a tad bit doubtful.

"You sparked my interest Luigi, as I spied on you as you went along your merry little way throughout the mansion, not only did your cute little moustache catch my attention, but your sudden courage whenever it came to ghosts did as well. You know, it’s not every century you run into a living being who isn’t frightened by ghosts...Well, there _was_ your brother but he’s a different story.”

(It was true that Luigi’s phobia of ghosts slowly, yet surely diminished the more time he spent within the walls of the mansion, but that didn’t mean that he wasn’t still cautious, and possibly even a bit petrified whenever it came to the supernatural. He just simply grew accustomed to most of the ghosts residing within the building. However, when it came down to ‘portrait ghosts’, as E.Gadd liked to call them, or even King Boo himself, he was always wary as he had no possible idea what they were capable of. Nonetheless, he still tried to act brave whenever he was confronted as he believed that would have been what his brother would have wanted. That’s why he’s even here in the first place...)

"Y-You're point?"

"The point is, although in the beginning, I completely despise you and wanted you trapped inside a portrait for all of entirety, right now, I cannot help but admire you in some way. Even possibly adoring you if you really think of it.” 

He began to faintly blush.

“Look, what I'm trying to say is that I couldn't stop thinking of you the moment you step foot within this mansion. No matter what I did, no matter how many times I tried to ignore you, my mind keeps coming back to you… Almost like I have a _crush_ on you in some sort of way..”

Luigi closed his eyes as he let out a sigh of relief, realizing that the boo wasn't going to harm him or his brother.

‘The Boo was right! All he did admit he has a crush on him!’

...

‘ _Oh, so the boo was right.’_

Luigi eyes shot wide open as he stared at the boo, "You? Have a crush on me? But how? It’s impossible!" he cried out quite flustered.

“I didn’t say I _had a_ crush on you,” King Boo sputtered, “I said I _might_ have a crush on you, I’m not even sure if this is the real deal or just simply a phase. But don’t worry, I believe I have just the plan to settle my nonexistent heart under control."

"Which is what exactly?!"

"I want you to go on one single date with me."

"Go on a date?!” He nearly passed out on sight, “ Look at yourself, you're a ghost! It'll never work out!"

The boo playfully pouted.

"Oh Luigi," he said appalled, placing one nub on top of his forehead dramatically, "I simply cannot believe you find me _so repulsive_ to look at. Thankfully, there's nothing a little magic can't fix."

With that, he snapped his ‘fingers’, and as soon as Luigi blinked, the boo was no more.

Instead, in front of him stood a human.

A human who had pale alice-blue skin accompanied by dark magenta eyes. His hair was white, and although albeit quite long, was nicely held together in a ponytail held together by a single ribbon. Not to mention he had a tiny bit of facial hair, nothing compared to Luigi of course . His outfit seemed to compromise of black pants with black boots, and a white Victorian era ruffled shirt. He also stood a couple of inches taller than Luigi, but he figured that could simply be the work of his shoes.

"Will this work? Sorry if I'm not that _professional_ looking," the male joked, dusting off both of his sleeves, "it's not often that I change into a human form, or hardly even _ever_ for that matter."

"No-No it's fine." Luigi stammered, his face fully red as he shifted his gaze onto the cobblestone floor to avoid eye contact. ( _God, in all his days spent in the Mushroom Kingdom, not once did he believe that he was going to find a boo attractive._ )

"Are you sure? Because if you’re not comfortable, I can always change my features, for example..”

Once again, the boo snapped his fingers, changing his form once more.

“Maybe this one’s a better fit.”

Luigi looked up from the ground to see, well..

To see himself.

It was like looking into the mirror, if only Luigi had ghastly pale skin, non natural colored eyes, fangs, and white hair, and upon further inspection, possibly even freckles.

“So, what do you think?” He said mimicking the plumber.

"I think I prefer the last one," Luigi responded, not sure whether or not he should be embarrassed or offended, "and do you always have to snap your fingers everytime you go from one form to the next?"

The boo crossed his arms, "No I do not, I just do it because it’s more magical whenever I do so. But, since not only you both hate this new form and my ‘ _special effects’_ , I guess I can make due without them.." He said shapeshifting back into his previous form.

"Now then,” he sighed, “Since we got that whole ‘situation’ taken care of, do we have a deal?" He said extending out his hand out to the plumber.

Luigi looked down and the individual’s hand before looking back at King Boo, "W-Wait, what's in it for me? I don’t even have to agree to this."

"Ugh, you humans. You always have to have some end of the bargain do you?" He said pinching the bridge of his nose annoyed, "How about this, not only will I let your brother go, but I will leave Peach’s kingdom alone. Although I cannot fully promise that, I will try my best in restraining myself from doing so."

"Wait, are you for real?" Luigi asked surprised.

"Yes, I am ‘for real’, now, do we have a deal or not?" 

Luigi took a deep breath in, ‘It’s just one date Luigi,’ he thought to himself, ‘just go on this one date with him and everyone you know will be _ok_.’

"It's a deal." he said as he shook the ghost’s hand.

"Well then, that settles it," King Boo stated letting go of Luigi’s hand as he proceeded to go grab Mario's portrait off of the wall.

"Meet back in Boo Woods tomorrow when night falls," He said tossing the portrait towards Luigi.

"Oh, and a couple of more things before you go…"

  
  
  



End file.
